Electrode, Secondary Battery Including the Electrode, and Method of Preparing the Electrode

Abstract

An electrode includes an electrode active material, wherein the electrode active material layer includes an electrode active material, polyvinylidene fluoride, and a conductive agent, wherein the conductive agent includes a carbon nanotube structure in which 2 to 5,000 single-walled carbon nanotube units are bonded to each other, and the carbon nanotube structure is included in an amount of 0.01 wt % to 0.5 wt % in the electrode active material layer. A secondary battery including the same, and a method of preparing the electrode are also provided.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application claims the benefit of Korean Patent Application Nos. 10-2018-0040574, filed on Apr. 6, 2018, and 10-2019-0040100, filed on Apr. 5, 2019, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.TECHNICAL FIELD[0002]The present invention relates to an electrode, a secondary battery including the same, and a method of preparing the electrode, wherein the electrode includes an electrode active material layer, the electrode active material layer includes an electrode active material; polyvinylidene fluoride; and a conductive agent, the conductive agent includes a carbon nanotube structure in which 2 to 5,000 single-walled carbon nanotube units are bonded to each other, and the carbon nanotube structure may be included in an amount of 0.01 wt % to 0.5 wt % in the electrode active material layer.BACKGROUND ART[0003]A typical example of an electrochemical device usin...

AI Technical Summary

Benefits of technology

The present invention is relating to an electrode for batteries that is made using a conductive agent dispersion with carbon nanotubes and polyvinylidene fluoride. The carbon nanotubes form a network structure that connects the active materials in the electrode, resulting in improved electrical conductivity and reduced resistance. The electrode is fixed to a current collector by the carbon nanotube network, improving adhesion. When used in a battery, the electrode exhibits excellent performance and lifespan. The electrode slurry used in the battery has lower powder resistance, further reducing resistance.

Problems solved by technology

Conventionally, a point-type conductive agent, such as carbon black, has mainly been used as the conductive agent for a secondary battery, but, with respect to the point-type conductive agent, there is a limitation in that an effect of improving electrical conductivity is not sufficient.

However, with respect to the line-type conductive agent such as a carbon nanotube or a carbon nanofiber, electrical conductivity is excellent, but, since dispersibility in the slurry is low due to the nature of the material itself growing in a bundle type or entangled type, there is a limitation in that coatability and processability are poor and the line-type conductive agent is not uniformly distributed in the electrode active material layer.

In order to address this limitation, attempts have been made to improve the dispersibility by introducing a functional group to the line-type conductive agent, but, in this case, since a surface side reaction occurs due to the presence of the functional group, electrochemical properties may be deteriorated.

Even with respect to the plane-type conductive agent such as graphene, electrical conductivity is excellent, but it may be difficult to prepare thin single layer graphene, and, in a case in which thick graphene is used, battery efficiency may be reduced.

Also, with respect to the plane-type conductive agent, electrolyte solution mobility may be limited in the battery due to a wide planar contact.

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